textproduct: Quad Cities

KEY MESSAGES

- A cold front will bring the risk of thunderstorms (30-70% coverage) today. The SPC has areas along and north of Highway 30 in far eastern Iowa and northwest Illinois under a Marginal Risk (Level 1 out of 5) for severe storms. Primary threats are damaging winds and hail.

- A pattern change this weekend will bring high humidity and above normal temperatures to the area. Heat headlines may be needed early next week (40-60% chance).

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 1254 AM CDT Wed Jun 24 2026

An occluded low pressure system over Minnesota is going to swing southeastward into Wisconsin today, pushing a cold front through the area. The displacement of the trough to our north and low amplitude of the front are expected to limit convective coverage to mainly along and north of Interstate 80 in the form of the scattered (40- 70%) showers and thunderstorms with more isolated coverage (20-30%) further south. Timing for these storms appear to be between 7am and 6pm, clearing west to east. There is the potential for a few severe storms where an overlap in steeper low and mid-level lapse will occur, enabling SBCAPE values of 1500-2000 J/kg. The 0-6 km bulk shear is also forecasted to peak around 40 knots north of Highway 30 along the front. With both shear and instability, the SPC has issued a Marginal Risk (Level 1 out of 5) for severe weather along and north of the Highway 30 corridor in far eastern Iowa and northwest Illinois with the primary threats being damaging winds and hail, but an isolated tornado cannot be ruled out.

The front clears the CWA after sunset as PoPs begin to drop off across northwestern Illinois. Northwesterly flow at the surface will start to advect in cooler and drier air, leading to a more comfortable Thursday with dew points back into the mid 50s to low 60s and highs in the 70s, similar to Tuesday. Some precipitation should stick around as weak surface troughing on the backside of the low pressure, now over the Great Lakes region, provides the subtle lift for light showers across east- central Iowa and northwest Illinois. There is also some uncertainty among model guidance on the presence of some light stratiform rain developing south of Highway 34 on Thursday. A mid-level shortwave is anticipated to deepen a low pressure near the Oklahoma panhandle and develop a weak warm front over Kansas and central Missouri, but this source of lift may not be sufficient to support widespread coverage in our southern CWA. Regardless, no severe weather is expected Thursday.

By Thursday night, a high pressure sets up north of us over northern Minnesota and south-central Canada, leading to mostly dry conditions along and north of Interstate 80. The low pressure in the Southern Plains shifts into Kansas. Light showers will remain possible (40-60%) south of Highway 34 as the warm front inches northward and the shortwave approaches the Mid- Mississippi River Valley. Rainfall amounts should be small, ranging from a trace to a quarter of an inch (>80% chance).

LONG TERM /FRIDAY THROUGH TUESDAY/

Issued at 1254 AM CDT Wed Jun 24 2026

Friday...The mid-level shortwave passes through Missouri and loses most of its amplitude, essentially limiting it to a band of shear vorticity. The low pressure over Kansas will struggle to reach Missouri as the warm front transitions to a stationary boundary. Showers once again remain linger south of Highway 34 (40-60% coverage) with similar or slightly higher accumulations compared to Thursday night. By Friday evening, the entire CWA should be dry with a ridge building over the Northern Plains and subsidence from the high pressure over the Great Lakes.

Saturday-Tuesday...The weekend and the beginning of next week looks to be toasty as longwave ridging sits over the entire Mississippi River Valley. A deep low heights center will dig into the western CONUS and propagate slowly eastward through Tuesday. Pressure falls along the entire length of the Rockies is expected to strengthen southerly low-level flow from Texas up to Minnesota. This will kick off a warming and moistening trend on Saturday with highs and dew points climbing through Monday. Heat headlines (heat indices greater than 100 degrees) may be needed early next week (40-60% chance per the 23.12z LREF run). Ensemble guidance has the ridge tilting eastward by Tuesday, opening the door for a shortwave trough passage. With such a warm and moist environment present over the CWA, any source of lift will pose a threat for severe weather heading into the middle of next week.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 1247 AM CDT Wed Jun 24 2026

VFR conditions are forecasted to persist through the entire TAF period outside the potential for isolated-to-scattered showers and thunderstorms along a cold front near KCID, KDBQ, and KMLI during the morning and afternoon. As this front clears all sites from west-northwest to east-southeast, the winds will shift from southerly to westerly and increase from 5 knots to 10 knots by 18z. A VFR mixed-layer cloud deck is expected with the front: a SCT-to-BKN deck around 5 kft and a BKN-to-OVC around 10 kft. Ceilings and visibility could approach MVFR conditions with heavier thunderstorms along the front, but the disorganization of the line warranted just PROB30s. Later in the afternoon, additional storms could develop near KDBQ and KMLI, but again, they will be isolated in nature.

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.